Table 1.

OMERACT MRI in RA group’s updated 2016 recommendations of a “core set” of basic MRI sequences and MRI definitions of important RA joint pathologies for use in the RA MRI scoring system (OMERACT 2016 RAMRIS).

“Core set” of basic MRI sequences:
It is suggested that future MRI studies, which intend to assess inflammatory and destructive changes in RA joints, should include at least the following:
  • T1-weighted images before and after IV gadolinium-contrast injection* that enable visualization in 2 planes**

  • T2-weighted fat-saturated or STIR images

Definitions of important RA joint pathologies:
  • Synovitis: An area in the synovial compartment that shows above-normal postgadolinium enhancement (signal intensity increase) of a thickness greater than the width of the normal synovium

  • MRI bone erosion: A sharply marginated bone lesion, with correct juxtaarticular localization and typical signal characteristics, which is visible in 2 planes with a cortical break seen in at least 1 plane††

  • MRI osteitis/bone marrow edema: A lesion within the trabecular bone, with ill-defined margins and signal characteristics consistent with increased water content‡‡

  • MRI joint space narrowing: Reduced joint space width compared to normal, as assessed in a slice perpendicular to the joint surface

  • MRI tenosynovitis: Peritendinous effusion# and/or tenosynovial postcontrast enhancement##, seen on axial sequences over ≥ 3 consecutive slices

  • * IV gadolinium injection is particularly important if assessment of synovitis is considered important.

  • ** Bi-planar imaging can be achieved by a 2-dimensional sequence in 2 planes or a single 3-D acquisition with isometric voxels allowing reconstruction in multiple planes. A dedicated cartilage sequence, e.g., a fat-suppressed 3-D gradient echo sequence, will improve cartilage assessment.

  • On T1-weighted images: discontinuity of the signal void of cortical bone and loss of normal high signal intensity of bone marrow fat. Rapid post-gadolinium enhancement suggests presence of active, hypervascularized pannus tissue in the erosion.

  • †† Other focal bone lesions and variations of normal anatomy must obviously be considered, but are generally distinguishable with associated imaging and clinical findings.

  • May occur alone or surrounding an erosion.

  • ‡‡ High signal intensity on T2-weigted fat-saturation or STIR images, and low signal intensity on T1-weighted images.

  • # High signal intensity on T2-weigted fat-saturated/STIR images.

  • ## Enhancement (signal intensity increase) is judged by comparison of T1-weighted images obtained before and after IV gadolinium-contrast. OMERACT: Outcome Measures in Rheumatology; MRI: magnetic resonance imaging; RA: rheumatoid arthritis; RAMRIS: Rheumatoid Arthritis Magnetic Resonance Imaging Scoring system; IV: intravenous; STIR: short-tau inversion recovery.